> Do you even remember the name of the king that queen elizabeth inherited? When he died?
I'm not at all invested in the royal family, but I think this question actually makes the point of why it's a big deal: she's been the queen for such a long time that very few people alive can remember a time when she wasn't the queen. It marks the end of a long era.
Generally I agree with the sentiment, but at the same time this is impactful, because this is a person that has been in the public eye for people's entire lives, so it presents as somewhat of a shock. It's a reminder that the only constant is change and that death comes for us all... at least that's why I think many people have a strong reaction to the news. My personal reaction is "meh".
As for how major a historical event Elizabeth II's passing is, only history can tell and history tells it's stories with a delay, so we'll have to see. It could mark the beginning of the end of the monarchy in the UK, for example, which in turn could coincide with other major changes.